LU-5319 mdt: pass __u64 for storing opdata

LU-5319 mdt: pass __u64 for storing opdata

While lcd_last_data is only __u32, the internal disposition handling
is done with __u64, so it doesn't makes sense to drop the high bits in
mdt_get_disposition(), mdt_set_disposition(), mdt_clear_disposition().

Minor whitespace and prototype cleanups.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: Ia4880b7256564a6799f8c686fd8690ebbf3ebbe5
Reviewed-on: http://review.whamcloud.com/13297
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Grégoire Pichon <gregoire.pichon@bull.net>
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>